Old relatives settled in North-Eastern heartlands (12)

'old relatives' is the definition.
The definition and answer can be both animals as well as being plural nouns.
Perhaps there's an association between them I don't understand?

'settled in north-eastern heartlands' is the wordplay.
I cannot quite understand how this works, but
'north' could be 'n' (synonyms) and 'n' is found within the answer.
'eastern' could be 'e' and 'e' is found within the answer.
an anagram of 'heartlands' is 'anderthals' which is within the answer.
No letters remain.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?